Fiber optic cable is often installed for use under harsh environmental conditions. Harsh environmental conditions may include installations in locations where the fiber optic cable is exposed to groundwater. The groundwater may be fresh or salt water, and salt water is known to be particularly debilitating to fiber optic cables. For example, if a fiber optic cable outer casing cracks or otherwise develops a water pathway from an exterior surface to an interior surface surrounding the rest of the cable, water incursion into the interior of the fiber optic cables may damage the interior optical fibers, necessitating repairs. Such damage may take place with water in its liquid form. Moreover, in locations where the fiber optic cable is buried above the frost line, water may penetrate the fiber optic cable and change into a solid state, damaging the fibers as the liquid expands into its solid state. In addition, cables with frozen liquids in them are particularly difficult to repair or service, and may need to be thawed prior to servicing.
To minimize the likelihood of water incursion into a fiber optic cable and subsequent damage to the interior optical fibers, an oil-based gel may be disposed around the optical fibers, both to repel water and to keep the fibers from contacting the water. The oil-based gel typically extends longitudinally through the interior of the fiber cable, coating the length of the fibers. A gel may effectively prevent any liquid from contacting the fibers. However, in order to service or maintain the fiber optic cable, the fibers must first be clean. Oil-based gels are sticky and messy, making it difficult and time-consuming to remove the gel from the fibers.
An alternative method of minimizing the likelihood of water getting into a fiber optic cable is to dispose water absorbent material adjacent the fibers inside the fiber optic cables. However, the absorbent material can only absorb a limited amount of water based on the capacity and amount of absorbent material; and the absorbent material does not stop the water incursion. The fiber optic cable may still eventually fill with water.
Filling a fiber optic cable with a solid material by disposing the material longitudinally along the length of the fibers to prevent liquids from contacting the fibers would result in a cable that is very heavy, stiff and unwieldy, and thus difficult to maintain or service. Depending on the material used, it could also bond the fibers together. As the solid material surrounding the fibers in the section to be serviced would have to be removed in prior to servicing the cable, this would make it difficult to separate the fibers for maintenance.